Experimental infection of Black Belly and INRA 401 straight and crossbred sheep with trichostrongyle nematode parasites

Gruner, L.; Aumont, Gilles; Getachew, Tesfaye; Brunel, Jean-Claude; Péry, Christophe; Cognie, Y.; Guérin, Y.

doi:10.1016/j.vetpar.2003.07.005

Cited by 49 publications

(27 citation statements)

References 15 publications

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“…The negative impact of host genetic resistance on H. contortus mortality rate and female fertility corroborates previous results comparing resistant and susceptible breeds [78, 79] or lines of sheep with divergent resistance status [62, 80]. Such an observation also links with the proposed framework for the immune response against T. circumcincta [81].…”

Section: Discussionsupporting

confidence: 88%

Meta-analysis of the parasitic phase traits of Haemonchus contortus infection in sheep

et al. 2017

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BackgroundThe parasitic nematode Haemonchus contortus shows highly variable life history traits. This highlights the need to have an average estimate and a quantification of the variation around it to calibrate epidemiological models.MethodsThis paper aimed to quantify the main life history traits of H. contortus and to identify explanatory factors affecting these traits using a powerful method based on a systematic review and meta-analysis of current literature. The life history traits considered are: (i) the establishment rate of ingested larvae; (ii) the adult mortality rate; (iii) the fertility (i.e. the number of eggs laid/female/day); and (iv) fecundity of female worms (i.e. the number of eggs per gram of faeces).ResultsA total of 37 papers that report single experimental infection with H. contortus in sheep and published from 1960 to 2015, were reviewed and collated in this meta-analysis. This encompassed 115 experiments on 982 animals. Each trait was analysed using a linear model weighted by its inverse variance. The average (± SE) larval establishment rate was 0.24 ± 0.02, which decreased as a function of the infection dose and host age. An average adult mortality rate of 0.021 ± 0.002) was estimated from the literature. This trait varied as a function of animal age, breed and protective response due to prior exposure to the parasite. Average female fertility was 1295.9 ± 280.4 eggs/female/day and decreased in resistant breeds and previously infected hosts. Average faecal egg count at necropsy was 908.5 ± 487.1 eggs per gram of faeces and varied as a function of infection duration and host resistance. The average sex ratio of H. contortus was 0.51 ± 0.006.ConclusionThis work is the first systematic review to summarise the available information on the parasitic phase of H. contortus in sheep. The results of the meta-analysis provide robust estimates of life history traits for parametrization of epidemiological models, their expected variation according to experimental factors, and provides correlations between these.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-017-2131-7) contains supplementary material, which is available to authorized users.

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Section: Discussionsupporting

confidence: 88%

Meta-analysis of the parasitic phase traits of Haemonchus contortus infection in sheep

et al. 2017

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“…Considerable variation has been reported among sheep breeds on their ability to resist gastro-intestinal nematodes (GIN). For example, indigenous sheep breeds like Red Maasai [6], Garole [7], Gulf Coast Native [8], Rhon [9] and Barbados Black Belly [10] were found to have relatively better resistance against GINs. Similarly, within-breed genetic variation has also been demonstrated in diverse sheep populations including Merino [11], Romney [12], Scottish Blackface [13], feral Soay sheep [14], etc.…”

Section: Introductionmentioning

confidence: 99%

Candidate Gene Approach for Parasite Resistance in Sheep – Variation in Immune Pathway Genes and Association with Fecal Egg Count

et al. 2014

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Sheep chromosome 3 (Oar3) has the largest number of QTLs reported to be significantly associated with resistance to gastro-intestinal nematodes. This study aimed to identify single nucleotide polymorphisms (SNPs) within candidate genes located in sheep chromosome 3 as well as genes involved in major immune pathways. A total of 41 SNPs were identified across 38 candidate genes in a panel of unrelated sheep and genotyped in 713 animals belonging to 22 breeds across Asia, Europe and South America. The variations and evolution of immune pathway genes were assessed in sheep populations across these macro-environmental regions that significantly differ in the diversity and load of pathogens. The mean minor allele frequency (MAF) did not vary between Asian and European sheep reflecting the absence of ascertainment bias. Phylogenetic analysis revealed two major clusters with most of South Asian, South East Asian and South West Asian breeds clustering together while European and South American sheep breeds clustered together distinctly. Analysis of molecular variance revealed strong phylogeographic structure at loci located in immune pathway genes, unlike microsatellite and genome wide SNP markers. To understand the influence of natural selection processes, SNP loci located in chromosome 3 were utilized to reconstruct haplotypes, the diversity of which showed significant deviations from selective neutrality. Reduced Median network of reconstructed haplotypes showed balancing selection in force at these loci. Preliminary association of SNP genotypes with phenotypes recorded 42 days post challenge revealed significant differences (P<0.05) in fecal egg count, body weight change and packed cell volume at two, four and six SNP loci respectively. In conclusion, the present study reports strong phylogeographic structure and balancing selection operating at SNP loci located within immune pathway genes. Further, SNP loci identified in the study were found to have potential for future large scale association studies in naturally exposed sheep populations.

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“…Elle se caractérise par un nombre réduit de vers adultes, une plus grande proportion de larves inhibées et par des femelles plus petites et moins fécondes. La variation du nombre de globules leucocytes (mastocytes dégranulés en position intraépithéliale) explique un tiers de la variation du nombre de vers, tandis que la variation de la réponse IgA dans la muqueuse abomasale explique 40 % de la variation de la longueur et de la fécondité des femelles (Stear et al 1995 (Gruner et al 2003 ;Terefe et al 2007c). Des variations génétiques très importantes ont également été notées entre individus au sein des races Merinos (Woolaston & Piper, 1996) ou INRA 401 (Gruner et al 2002), ce qui signi-fie qu'une sélection sur un critère héritable comme l'excrétion d'oeufs est réalisable au sein de nombreuses races comme l'attestent les publications mentionnées ci-dessus.…”

Section: Les Interactions Entre Les Hôtes Et Les Strongles Gastro-intunclassified

La résistance génétique des ovins aux strongles gastro-intestinaux

Jacquiet¹,

Barillet²,

Bouix³

et al. 2009

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La sélection génétique d'animaux résistants aux strongles gastro-intestinaux est une des réponses possibles au développement des résistances aux anthelminthiques dans les élevages ovins. Sa mise en oeuvre pratique est possible dès maintenant grâce à l'estimation de l'intensité de l'excrétion d'oeufs dans les matières fécales en infestations naturelles ou artificielles. Toutefois, cette technique est trop lourde à développer sur de très grands effectifs. La sélection assistée par marqueurs proches de gènes de résistance ou encore mieux par les mutations des gènes eux-mêmes pourrait prédire la valeur génétique d'un individu à la naissance sans passer par une mesure ultérieure de son phénotype. Les outils moléculaires de cette sélection sont actuellement à l'étude. Les limites potentielles de la sélection génétique sur la résistance aux nématodes gastro-intestinaux, comme une plus grande sensibilité à d'autres pathogènes (virus, bactéries ou protozoaires) ou une adaptation des parasites à des hôtes résistants, sont abordées et discutées.

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Experimental infection of Black Belly and INRA 401 straight and crossbred sheep with trichostrongyle nematode parasites

Cited by 49 publications

References 15 publications

Meta-analysis of the parasitic phase traits of Haemonchus contortus infection in sheep

Meta-analysis of the parasitic phase traits of Haemonchus contortus infection in sheep

Candidate Gene Approach for Parasite Resistance in Sheep – Variation in Immune Pathway Genes and Association with Fecal Egg Count

La résistance génétique des ovins aux strongles gastro-intestinaux

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